In a heavy duty tire for use with trucks, buses and the like, the tread portion is conventionally provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire axial direction. By these grooves, various performances required for the tire such as wet performance, rolling resistance and uneven wear resistance are enhanced.
For example, in the following Patent Document 1, there is disclosed a heavy duty tire provided in the tread portion with hexagonal blocks divided by a plurality of main grooves extending in a zigzag shape (circumferential grooves 10, 11 and circumferential narrow groove 24 in the document), and a plurality of lateral grooves (lug grooves 25, 26, 27 in the document). Such tire can reduce tire noise, while improving wet performance and uneven wear resistance.
Further, in the following Patent Document 2, there has been proposed a heavy duty tire provided in the tread portion with a plurality of blocks having a substantially hexagonal shape. In this heavy duty tire, an effect is expected such that, by mutually shifting edges of the respective blocks so as to strike a road surface at different timings, the sound when the blocks strike the road surface is changed to white noise.